Added namespaces in the newly C++ified AEC code

webrtc/modules/audio_processing/aec/echo_cancellation.h

 /*
  *  Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
 #ifndef WEBRTC_MODULES_AUDIO_PROCESSING_AEC_ECHO_CANCELLATION_H_
 #define WEBRTC_MODULES_AUDIO_PROCESSING_AEC_ECHO_CANCELLATION_H_
 
 #include <stddef.h>
 
 #include "webrtc/typedefs.h"
 
+namespace webrtc {
+
 // Errors
 #define AEC_UNSPECIFIED_ERROR 12000
 #define AEC_UNSUPPORTED_FUNCTION_ERROR 12001
 #define AEC_UNINITIALIZED_ERROR 12002
 #define AEC_NULL_POINTER_ERROR 12003
 #define AEC_BAD_PARAMETER_ERROR 12004
 
 // Warnings
 #define AEC_BAD_PARAMETER_WARNING 12050
 
@@ skipping 199 matching lines @@
 // Returns a pointer to the low level AEC handle.
 //
 // Input:
 //  - handle                    : Pointer to the AEC instance.
 //
 // Return value:
 //  - AecCore pointer           : NULL for error.
 //
 struct AecCore* WebRtcAec_aec_core(void* handle);
 
+}  // namespace webrtc
+
 #endif  // WEBRTC_MODULES_AUDIO_PROCESSING_AEC_ECHO_CANCELLATION_H_